Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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156 FXUS64 KJAN 131751 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 1251 PM CDT Sat Jul 13 2024 ...New AVIATION... .MESOSCALE UPDATE... Issued at 1034 AM CDT Sat Jul 13 2024 Previous forecast largely on track. Heat and humidity continue to creep upwards, with analyzed PWAT values currently at 1.5 inches or greater south of a Bastrop, LA to Meridian, MS line. A positively-tilted upper-level trough over the central CONUS is keeping southwesterly flow aloft over our region and is resulting in about 15-20 kts of deep-layer wind shear over the area. Mid- level ridge over the southeastern U.S. will limit instability from northeast MS eastward into AL, but increasing moisture and even minimal instability will support a chance for isolated showers or a thunderstorm into northern Mississippi today. Have added isolated showers and storms to the forecast for all zones this afternoon, with better chances south of Interstate 20 with the better instability and moisture. With some flow aloft, precip chances will linger into the evening especially in the south. A Heat Advisory remains in place today and tomorrow where heat index values are expected to top out in the 105 to 110 range. /NF/ && .DISCUSSION... Issued at 336 AM CDT Sat Jul 13 2024 Today and tonight... Southwest flow regime will persist this weekend, with moist Gulf air building northward. Look for increasing dewpoints through the period. This along with surface temperatures in the upper 90s to near 100 will result in heat indices around 105, thus a heat advisory has been hoisted for the southwestern half. Further northeast, drier air lingers, allowing for deeper mixing, keeping dewpoints in the 60s, limiting greater heat stress today. This area will eventually get their share though early next week. Mostly diurnal convection should be confined to along and south of the I-20 corridor this afternoon where greater moisture is available. A few showers could linger after sunset as heating wanes leading to an otherwise quiet night./SAS/ Sunday through Wednesday: Mid level ridging over the Southeast and a surface high over the northern Gulf will serve as primary influences over the first half of the new week. Thanks to the ridge, daytime temps in the mid 90s to near 100 will remain common across the area. As we remain just on the western side of the ridge axis, low level trajectories will maintain a seasonably moist airmass across the region. This will provide the fuel for mainly diurnally driven convection over the first half of the week. In most areas, development will occur too late in the day to disrupt heating before heat indices reach crucial levels, so heat stress will remain a concern during this time frame. A Heat Advisory will likely be needed for at least some portion of the area each day, barring some change in precip timing. We have gone ahead and extended the current Heat Advisory into Sunday, and some expansion in area is possible at a later time. Thursday and Friday: A pattern change is in the offing for the latter half of the week as an upper trough over the Upper Midwest dips further southward across the country. This will bring a cold front southward into the Mid South around Friday. Much like the other weak summertime cold fronts we have seen in recent weeks, this one will likely stall near or just north of the area as it loses upper level support. However, it would likely still serve as a forcing mechanism for greater rain chances at the end of the week, resulting in some downward trend in daytime high temps and heat stress. A brief intrusion of slightly drier air is also possible mainly over the northern half of the area. This time of year, we`ll take what we can get. /DL/ && .AVIATION... (18Z TAFS) Issued at 1251 PM CDT Sat Jul 13 2024 VFR ceilings will prevail across central MS to start off the TAF period. Weather conditions will remain quiet through 18Z with mid to high clouds expected. Scattered SHRA and TSRA will be possible mainly across south MS and central LA starting around 20Z Saturday, which will result in brief sub-VFR conditions across southern TAF sites (mainly HBG, PIB and HEZ). Elsewhere, some isolated SHRA could occur across north and central MS around this timeframe. Showers will begin to diminish around 02Z Sunday with VFR ceilings expected through 11Z Sunday. Some light patchy fog will be possible across south MS starting around 06Z Sunday and will last through 12Z Sunday. Scattered SHRA and TSRA will make a return across south MS starting around 15Z Sunday before becoming widespread Sunday afternoon. /CR/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 76 95 76 95 / 10 50 20 60 Meridian 74 98 74 96 / 20 50 20 60 Vicksburg 75 94 75 96 / 10 40 10 30 Hattiesburg 76 97 76 96 / 30 70 10 60 Natchez 74 93 75 94 / 20 50 10 40 Greenville 76 94 76 96 / 10 30 10 20 Greenwood 76 96 75 96 / 10 30 10 30 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Heat Advisory until 7 PM CDT this evening for MSZ040-041-047>049- 053>057-059>066-072>074. Heat Advisory from 10 AM to 7 PM CDT Sunday for MSZ040-041- 047>049-053>057-059>066-072>074. LA...Heat Advisory until 7 PM CDT this evening for LAZ007>009-015-016- 023>026. Heat Advisory from 10 AM to 7 PM CDT Sunday for LAZ007>009-015- 016-023>026. AR...None. && $$ SAS/DL/CR/NF